WiX - Custom Action (after installation) does not run on upgrade

Question

I have created a custom action that gets triggered via UI. It works fine for new install but fails during upgrade. However, if I run a repair from control panel, it then runs fine. I tried capturing msi log but it does not give any clue. Here are the snippets...

UI:

<Control Id="CloseButton" Type="PushButton" X="230" Y="243" Width="66" Height="17" Default="yes" Cancel="yes" Text="&amp;Continue">    
  <Publish Event="DoAction" Value="ConfigureServer1">1</Publish>   
  <Publish Event="EndDialog" Value="Return">1</Publish>    
</Control>

Custom Action:

<CustomAction Id="ConfigureServer1" Impersonate="no" Directory="TARGETDIR" Return="asyncNoWait" ExeCommand="[#fileSetupDb] &quot;[ProductVersion]&quot; &quot;[OCISUPGRADE]&quot;"></CustomAction>

Sequence for the UI file:

<InstallUISequence>
......
 <Show Dialog="FinishedForm" OnExit="success" />
......
</InstallUISequence>

Any clues.... or anything I can try to debug etc.? I tried for a couple of days with no results. I am not a newbie in msi or wix and not an expert either.